The proposed research is to study factors that affect transcription of yeast transposable (Ty) elements or of their delta terminal repeats. Transcription of Ty or delta elements makes adjacent genes mutant. Suppressors of these insertion mutations are mutations in SPT genes (SPT = suppressor of Ty) that alter transcription of Ty and delta elements. The long term goals are to understand the functions of SPT genes in Ty-mediated and other cellular transcription. The specific aims of this proposal are to study three sets of spt genes. Mutations in these three sets of genes alter transcription of Ty and delta elements in distinct ways and have other pleiotropic effects. The first set of genes, SPT3, SPT7 and SPT8, is required for transcription initiation in delta sequences. SPT7 and SPT8 will be cloned, sequenced and analyzed genetically as has been done for SPT3. Similar analysis will be done for RSP1, an essential gene identified by mutations that suppress spt3 mutations. Further study will include: determination if the products encoded by these genes bind to delta sequences; analysis of the interaction between these genes by use of transcriptional analysis, antibodies, and mutant analysis; and isolation and analysis of cis-acting mutations in delta sequences followed by identification of pseudorevertants in trans-acting factors. The second set is SPT6, an essential gene. Mutations in SPT6 affect transcription of a diverse set of genes. Study of SPT6 will include analysis of Ty-lacZ fusions to define the spt6 transcriptional defect and construction and analysis of linker insertion mutations in SPT6 to identify different phenotypes conferred by mutations throughout this large gene. Mutations in the third set, SPT16 and SPT17, have novel transcriptional alterations. These two genes will be cloned, null mutations will be constructed and the genes will be mapped. The nature of the defects will be analyzed by genetic and transcriptional analysis. The proposed experiments will provide genetic and molecular characterization of these transcription factors and will yield important information on transcriptional mechanisms.